Early Period Georg Jensen Amber Brooch # 40

This has all the early hallmarks of Georg Jensen. GJ and 850 silver and the number 40. This great fish eating its tail has a beautiful amber cabochon. I have had several of this style and number but never with amber.
For me, the fact that it has a plunger back and early marking makes it all that more valuable. And the condition is mint.
The brooch is 1 3/16" in diameter.